Sometimes when debugging SMTP issues the standard maillog is not enough and I need to see the full SMTP session. In postfix I add the problematic IP to "debug_peer_list" which will enable the session log and other debug information for only that IP.

Is there a similar thing in exim? I have only found references to "running exim in debug mode" which apparently causes ALL sessions to be logged which I fear will quickly write tons of unnecessary logs, cause heavy disk I/O, and make it hard to find the transaction in question

TL;DR:What is the best way to get a full SMTP transaction log from a specific IP (or sender address) ?

But if you want to see in the logs what your side is saying too, that's not possible inside exim. Your options are then constrained to any system provided network debugging tools, such as tcpdump, tshark, or (my favorite) ngrep.

As an example, if you have a customer who complains they cannot send mail through your server. Here's a simple entry that shows why they are unable to send:

very informative, thanks! "not possible" is not the answer I was hoping for obviously, but having one side of the chat protocol is already something. I currently use network debuggers for this task, its just a PITA to dissect the TLS sessions, so I was looking for a simpler solution within the MTA
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GryphiusJan 1 '13 at 14:43